Endoscopes are long, tubular instruments used to examine endoluminally distant, confined spaces in humans, animals or in various types of equipment. Endoscopes are flexible, carry a powerful light which illuminates the passage to be examined from the tip of the endoscope, possess either fibreoptic or video image acquisition ports, and contain a series of channels running throughout their length to allow air insufflation, water injection and insertion of tubular instruments, such as forceps, snares, needles or retrieval forceps among others.
Insertion of endoscopes, or similar devices such as boroscopes, gastroscopes, colonoscopes or enteroscopes, as used in examination of narrow passages, whether it be within human or animal bodies or in narrow spaces within machinery is relatively simple over short distances but progressively more difficult with increasing distance of insertion. For example, gastroscopy in humans is easily achieved by using a relatively stiff endoscope with a flexible end which can rapidly reach the second part of the duodenum. However, to continue introducing such an instrument beyond the duodenum becomes increasingly difficult because, despite the relative stiffness of the instrument, it loops within the stomach as it is inserted more deeply.
Although enteroscopes have been developed to traverse the small bowel, stiffening tubes (known as overtubes) are needed to stiffen the instrument within the stomach so that looping will not occur.
Colonoscopes are readily passed through the rectum and left-side of the colon but difficulties can arise when one wants to routinely reach the caecum or terminal ileum.
In other words, there is an increasing difficulty in reaching more distal parts of the bowel in people or distal parts of a confined space when attempting to introduce any type of endoscope into a confined space. Further, in working with human endoscopes there is also the need for rapid insertion to minimise human suffering and to minimise the possibility of rupture.
Self-advancing endoscopes are disclosed in U.S. Pat. Nos. 4,934,786, 5,345,925 and 5,562,601. The devices disclosed in these patents all rely on the outer surface of the endoscope having a relatively movable portion that grips the internal wall of the passage through which the endoscope is passing. In this way, they do not only rely on external pushing as their source of forward (advancing) motion. However, the devices disclosed are all relatively complex in construction.